Last fall, after Buffett wrote his controversial op-ed calling for higher tax rates on the very rich ("Stop Coddling the Super-Rich"), McConnell suggested that if Buffett is "feeling guilty" about his tax rate he should "send in a check" to the Treasury.

That line had become very popular among Buffett's conservative critics.

"I thought of offering to match the total amount — if we go to a contribution system — I'll match the total contribution made by all Republican members of Congress, and I'll even go three for one with McConnell. (Laughs.)

It's kind of touching this faith he has in the American public, that with a one-point two or three trillion dollar deficit that he thinks Americans are so wonderfully spirited that they would just solve it all by contributions. That is a tax policy only a Republican could come up with. So Mitch — and he's got this line, he's got this proposal out there — I would definitely, it's a firm offer, all the Republican members of Congress and like I say, I'm willing to triple his. I'll match the rest of them."

(You can hear Buffett's comments, along with some others on different topics, courtesy audio files Time has included in its online story.)

Time notes, "That could be quite a bill if McConnell takes the challenge; after all, the Senator is worth at least $10 million."